Ultralow Absorption Coefficient and Temperature Dependence of Radiative Recombination of CH₃NH₃PbI₃ Perovskite from Photoluminescence

Abstract

Spectrally resolved photoluminescence is used to measure the band-to-band absorption coefficient α_BB(ℏω) of organic–inorganic hybrid perovskite methylammonium lead iodide (CH₃NH₃PbI₃) films from 675 to 1400 nm. Unlike other methods used to extract the absorption coefficient, photoluminescence is only affected by band-to-band absorption and is capable of detecting absorption events at very low energy levels. Absorption coefficients as low as 10^–14 cm^–1 are detected at room temperature for long wavelengths, which is 14 orders of magnitude lower than reported values at shorter wavelengths. The temperature dependence of α_BB(ℏω) is calculated from the photoluminescence spectra of CH₃NH₃PbI₃ in the temperature range 80–360 K. Based on the temperature-dependent α_BB(ℏω), the product of the radiative recombination coefficient and square of the intrinsic carrier density, <i>B</i>(<i>T</i>) × <i>n</i>_<i>i</i>², is also obtained